Philodendron auriculatum Standl

Philodendron auriculatum Standl. & L. O. Williams,

Ceiba 3: 108. 1952. TYPE: Costa Rica. Puntarenas: Esquinas forest preserve, Esquinas Experiment Station, region between Río Esquinas and Palmar Sur de Osa, 60 m, Allen 5697 (holotype, EAP; isotypes, F, US). Figures 12, 20, 23, 65, 69--72.

Usually epiphytic, sometimes epilithic, rarely terrestrial; stem appressed-climbing, creeping, leaf scars conspicuous, 2.5--3 cm long, 2.5--3.5 cm wide; internodes short, scurfy, 1--4 cm long, 1.5--5.5 cm diam., usually broader than long, dark green, drying becoming light tan with age; roots purplish maroon at base, brownish green or yellow at apex, pubescent, tapered, slender, to 27 cm long, 3--4 mm diam., few per node, sometimes emerging through the cataphylls at the nodes; cataphylls subcoriaceous, sometimes moderately spongy, 13--50 cm long, sharply 2-ribbed, pale green, drying brown, several persisting intact, eventually deciduous, emarginate with subapical apiculum at apex.
LEAVES mostly erect or erect-spreading; petioles 24--53 cm long, 7--23 mm diam., erect to spreading, subterete, more or less spongy, green, somewhat flattened at base adaxially, rounded abaxially, surface short, dark, green-lineate and with dark green ring at apex; blades usually oblong-oblanceolate, rarely oblong-elliptic, broadest from middle to above middle, with narrow auriculate lobes, subcoriaceous, bicolorous, acuminate at apex (the acumen inrolled), usually narrowly cordulate or auriculate at base, 37.5--75 cm long, 9--23 cm wide (3.3--4.2 times longer than wide), (1.4--1.6 times longer than petiole), broadest at the middle, upper surface dark green, drying pale yellow-green, semiglossy, lower surface slightly paler green, semiglossy; sinus 7--14 mm deep; midrib broadly convex at base becoming flattened toward the middle, eventually weakly sunken at apex above, green, with dark green lineations, midrib convex at base, eventually narrowly convex at apex below, green-striate, paler than surface; primary lateral veins 7--10(11) per side, departing midrib at a 80--85E angle, more or less straight to the margins, sunken, concolorous above, raised to round-raised, paler than surface below; interprimary veins numerous, usually as conspicuous as primary lateral veins; minor veins arising mostly from the midrib, fewer from the primary lateral veins; lesser veins obscure above, fine, moderately conspicuous and darker than surface below.

INFLORESCENCES more or less erect, 1--2 per axil; peduncle 7--11.3 cm long, 9--11 mm diam., medium to pale green, unmarked, semiglossy; spathe erect-spreading, subcoriaceous, 13--14.5 cm long, (1.2--1.8 times longer than peduncle), weakly constricted midway (6 cm above base); spathe blade broadly flattened, curved weakly forward, pale greenish outside, to 9 cm long, (opening elliptic in face view, 5.5 cm wide), pale green, heavily suffused with red (B & K Red-Purple 3/10) throughout inside; spathe tube oblong-ellipsoid, medium to dark green outside, densely short lineate throughout outside, 6 cm long, 3.5 cm diam., red to maroon (B & K Red-Purple 3/10) at base, weakly so toward apex inside, spadix oblong (weakly tapered or weakly clavate), 11--24 cm long, broadest usually at the middle; pistillate portion medium to dark green, tapered toward the apex, 2.3--4.2 cm long, 2.7--4.3 cm long in front, 2.4--2.7 cm long in back, 8-12 mm diam. at apex, 9--15 mm diam. at middle, 5--7 mm wide at base; staminate portion 9.5--12 cm long; fertile staminate portion weakly tapered or weakly ellipsoid, 8--16 mm diam. at base, 10--16 mm diam. at middle, 6--10 mm diam. ca. 1 cm from apex, broadest at the middle or more or less uniform, broader than or as broad as the pistillate portion, as broad as the sterile portion; sterile staminate portion broader than or as broad as the pistillate portion; sterile staminate portion 0.7--1.5 cm diam.; pistils to 2.6 mm long, to 1.6 mm diam.; ovary 5--7(8--9)-locular, 0.7--1.2(2.1) mm long, (0.7)1.1--1.3 mm diam., with sub-basal placentation; ovules (3)4 per locule, 1-seriate (or in 2 series of 2), contained within translucent ovule sac, if present, 0.2--0.4 mm long, usually longer than funicle, style similar to style type B; style crown usually as broad as ovary; stigma discoid, 0.7--1 mm diam., 0.1--0.3 mm high, covering entire style apex; the androecium margins 4--6-sided and scalloped, 1--2.3 mm diam. at apex; thecae oblong (ellipical, slightly obovate); sterile staminate flowers irregularily rounded to bluntly 5-sided, 2.3--3 mm long, 1--1.5 mm wide, white.

INFRUCTESCENCE with berries orange.

Flowering phenology in Philodendron auriculatum is unclear but possibly flowering is initiated in the late rainy season. Only a single flowering collection exists (October) but there are a modest number of collections collected post-anthesis during the dry season and early rainy season (January through June). A single mature fruiting collection was made in January.

Philodendron auriculatum occurs only in southwestern Costa Rica on the Pacific slope from San José and Puntarenas Provinces (as far west as Carara), ranging from near sea level to 1200 m elevation in Tropical wet forest life zones.

Philodendron auriculatum is a member of P. sect. Calostigma subsect. Glossophyllum ser. Glossophyllum. This species is characterized by short internodes, sharply two-ribbed, deciduous cataphylls, moderately long, markedly spongy, somewhat flattened petioles (averaging slightly shorter than the blades), oblong-elliptic to oblong-oblanceolate, pale yellow-green-drying blades which are usually narrowly cordulate at base, and one to two greenish inflorescences which are red to maroon within at base.

Philodendron auriculatum is probably most closely related to P. pseudauriculatum Croat, which ranges along the Atlantic slope of Central America from Nicaragua to Panama and also on the Pacific slope of Panama near the Continental Divide (as well as the Serranía de Cañasas and Serranía de Pirre). That species differs in its usually darker gray-green drying leaf blades with a dark green ring at the apex of the petiole, and in having the leaf base acute, rounded or broadly subcordate at base (lacking the narrow auriculate lobes so common for P. auriculatum). In addition, P. pseudauriculatum has the whitish spathe clearly demarcated from the contrasting green peduncle. In contrast, P. auriculatum has a yellowish green spathe which is not at all demarcated from the peduncle.

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Additional specimens examined.

COSTA RICA. Puntarenas: near Inter-American Highway in vic. of Piedras Blancas, Croat 32956 (CR, MO); hills N of Palmar Norte, along trail to Jalisco, 50--700 m, Croat 35205 (MO); cove at NE base of peninsula, 3 km S of Puerto Quepos, 0 m, 9E24'N, 84E10'W, Grayum & Sleeper 6612 (CR, K, MO, US); El General Valley, along Río Sonador, near Pan-American Highway, 600 m, Williams et al. 28808 (F); along the Río Cacao above Pan-American Highway, 900 m, Williams et al. 28687 (F); Las Cruces Tropical Botanical Garden, Cantón Coto Brus, 6 km W of San Vito de Java, 1200 m, 8E49'N, 82E58'W, Croat 57268 (MO); 8.8 mi. N of Villa Neily, 1010 m, 66171 (MO); Osa Península, vic. Boscosa, Croat & Hannon 79297 (INB, MO); Esquinas Ridge, 150--250 m, Gómez 19677 (MO, NY, RSA, US); Rincón de Osa, Liesner 1819 (F, MO); ca. 5 km W of Rincón de Osa, 50--200 m, 8E42'N, 83E31'W, Burger & Liesner 7298 (F, MO, PMA); 7306 (CR, F); 50--200 m, 8E42'N, 83E31'W, Burger & Gentry 8978 (CR, F); 8E42'N, 83E31'W, Aguilar 1507 (INB, MO); Piedras Blancas-Rincón, 3.7 mi. W of Pan-American Highway, 90--105 m, 8E46'N, 83E18'W, Croat 67691 (MO); Quebrada Aparicio--Quebrada Aguabuena, Rincón de Osa, 200--400 m, 8E42'N, 83E31'W, Grayum et al. 4013 (MO); Chacarita-Rincón de Osa, ca. 6 km W of Inter-American Highway at Chacarita, 100 m, 8E45'N, 83E18'W, Croat & Grayum 59730 (CM, CR, K, MO, SAR); Parque Nacional Corcovado, Sirena, 0--150 m, 8E27-30'N, 83E33-38'W, Kernan 25 (CR, MO); Estación Sirena, S of Río Sirena along Río Camaronal, 0 m, 8E28'N, 83E35'W, Knapp 2188 (CR, L, MO, US); Talamanca Range, Pacific slope, forested foothills of mountains E of Quepos, 150--250 m, 9E29'N, 84E03'W, Burger et al. 10603 (F, MO). San José: Puriscal, Z.P. La Cangreja, 300 m, Morales et al. 3239 (CR, INB); Carara--El Sur de Turrubares, 280--370 m, 9E45'30"N, 84E32'W, Grayum 10445 (CR, INB, MO).